The field of art to which the claimed invention pertains is hydrocarbon separation. More specifically, the claimed invention relates to the separation of ortho aromatic isomers from a hydrocarbon feed stream containing a mixture of aromatics by use of a specific crystalline aluminophosphate adsorbent which selectively removes the ortho aromatic isomer from the feed stream. The selectively adsorbed ortho aromatic isomer is removed from the adsorbent through desorption.